Vapor chamber based on flat plate loop heat pipe

ABSTRACT

The present disclosure discloses a vapor chamber based on a flat plate loop heat pipe. The flat plate loop heat pipe composed of an evaporator, a reservoir and a gas/liquid line is pre-buried in an aluminum alloy plate, so as to form the vapor chamber based on the flat plate loop heat pipe. The evaporator of the flat plate loop heat pipe is arranged in a region, attached to a biggest heat source of a chip to be subjected to heat dissipation, on the vapor chamber, and the side, provided with a vapor channel, of the evaporator is attached to the biggest heat source.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of international applicationPCT/CN2017/000655, filed Oct. 31, 2017, which claims priority to ChinesePatent Application No. 201710257571.7 filed Apr. 19, 2017. Thedisclosures of these prior-filed applications are incorporated byreference in their entireties.

FIELD

The present disclosure relates to a vapor chamber, and moreparticularly, to a vapor chamber based on a flat plate loop heat pipe,and belongs to the technical field of electronic equipment heatdissipation.

BACKGROUND

A loop heat pipe is high-efficiency two-phase heat transfer equipment,and has the characteristics of high heat transfer performance,long-distance heat transfer, good temperature control, bendingarbitrariness, convenience in installation, etc. Due to many advantagesbeyond comparison over other types of heat transfer equipment, the loopheat pipe has a very broad application prospect in many fields such asaviation, aerospace and ground electronic equipment heat dissipation.

As shown in FIG. 1, the loop heat pipe mainly includes an evaporator 1,a condenser 2, a reservoir 3, a vapor line 4 and a liquid line 5. Thewhole cycle is as follows: liquid is evaporated on the outer surface ofa capillary wick 6 in the evaporator 1, and absorbs heat outside theevaporator 1, and then generates vapor flows from the vapor line 4 tothe condenser 2, and releases the heat in the condenser 2 to a heatsink, so as to condense the vapor into liquid, and finally the liquidflows into the reservoir 3 through the liquid line 5. A liquid workingfluid in the reservoir 3 is maintained being supplied to the capillarywick in the evaporator 1.

Because of the small space required for installation of a flat plateloop heat pipe, and the convenience of installing a flat plateevaporator and a heat source plane, it has been a research hotspot and akey application direction in recent years. Based on structures, flatplate loop heat pipes mainly fall into two forms. The first form is adisc-shaped flat plate loop heat pipe, where the evaporator is in a discshape, and the evaporator and the reservoir are separated by a capillarywick. The second form is a rectangular flat plate loop heat pipe, wherethe reservoir is arranged on one side of the evaporator.

A Vapor Chamber (VC) usually adopts a flat plate structure provided witha capillary wick. After the VC is filled with a working fluid,temperature equalization is realized through a gas-liquid phase changeof the working fluid. When the VC is used, heat sources (a chip orequipment) is attached to the VC, and heat conductive filler is used inthe installation interface. There are mainly two application forms:

1) a heat conductive VC: heat of one or more heat sources is conductedto one side or two sides (heat sink attached region as shown in FIG. 2)of a heat spreading plate, and then the heat is carried away in otherheat dissipation modes (water cooling, heat conduction and the like), asshown in FIG. 2; and

(2) a heat spreading VC: heat of one or more heat sources is uniformlyspread into other non-heat source regions of the whole VC to play atemperature equalization role and enlarge the heat dissipation area, andthen the heat is carried away in other heat dissipation modes such asair cooling or heat conduction, as shown in FIG. 3.

However, the application of the VC has the following issues: there is aconflict between improvement of the product properties and therequirement for the capillary wick. On the one hand, in order to improvecertain properties, it is desired that the capillary diameter is assmall as possible, because reducing of the capillary diameter of thecapillary wick can improve the maximum heat transfer capability,increase the maximum heat flux, improve the anti-overload andanti-gravity working capability and increase the size of the VC. On theother hand, in order to improve part of the properties, it is requiredthat the capillary wick obtains a relatively high permeability by usinga relatively large diameter and then increases the size of the VC, thatis, increases the length of the flow, so the flowing resistance needs tobe reduced, or decreases the thickness of the VC, that is, decreases theflowing sectional area, so the flowing resistance needs to be reduced.

SUMMARY

In view of the above, the present disclosure provides a vapor chamberbased on a flat plate loop heat pipe, so as to improve the heat transfercapability, the maximum heat flux and the anti-overload and anti-gravityworking capability of the vapor chamber, increase the size of a heatspreading plate and decrease the thickness of the vapor chamber, andsolve a conflicting requirement between the improvement of theproperties of the vapor chamber and the diameter of the capillary wick.

In the vapor chamber based on the flat plate loop heat pipe, the vaporchamber is attached to heat sources, and includes: a heat spreadingplate and a flat plate loop heat pipe composed of an evaporator, areservoir and a gas/liquid line. The flat plate loop heat pipe ispre-buried in the heat spreading plate. The evaporator is arranged onthe heat spreading plate at the position of attachment to the biggestheat source in the heat sources. The reservoir is used to supply liquidto the evaporator. Positions on the heat spreading plate that areattached to other heat sources except the biggest heat source in theheat sources are used as “heat source attached regions”, and positionson the heat spreading plate that are not attached to the heat sources,are used as “heat sink attached regions”. The gas/liquid line leadingout from an outlet of the evaporator is disposed in a meandering fashionbetween the “heat source attached regions” and the “heat sink attachedregions” on the heat spreading plate, so that a liquid working fluidenters the “heat sink attached regions” after absorbing heat of the“heat source attached regions” and being evaporated into vapor, and agas working fluid releases heat in the “heat sink attached regions” andis condensed into liquid; and circulation is performed hereby, and theworking fluid finally flows back into the reservoir after beingcondensed by the “heat sink attached regions” into liquid, therebyforming a loop.

As a preferable implementation of the present invention, cold sourcesare arranged in the “heat sink attached regions” on one side or twosides of the heat spreading plate. The gas/liquid line led out from theoutlet of the evaporator is disposed in a meandering fashion between the“heat sink attached regions” and the “heat source attached regions” onthe heat spreading plate.

As a preferable implementation of the present invention, the reservoiris suspended, and is not connected with the heat spreading plate in aheat conduction manner.

As a preferable implementation of the present invention, the evaporatoris exposed and directly attached to the biggest heat source in the heatsources.

As a preferable implementation of the present invention, the gas/liquidline is firstly formed by a copper, stainless steel or titanium alloypipeline sheet metal, and then pre-buried in the heat spreading plate ina gluing or welding manner.

Beneficial effects.

(1) The flat plate loop heat pipe may use a small-diameter capillarywick to provide higher capillary force, and external loops are all barepipes without capillary wicks, so that the flowing resistance is low;and finally the heat transfer capability, the maximum heat flux heatdissipation capability and the anti-overload and anti-gravity workingcapability of the vapor chamber may be improved, the size of the heatspreading plate may be increased, and the thickness of the vapor chambermay be decreased.

(2) Compared with a traditional vapor chamber structure, the vaporchamber of the present disclosure has the advantages that the thicknessof the vapor chamber is decreased by downsizing the evaporator and theline of the flat plate loop heat pipe, so as to satisfy an applicationoccasion with a smaller installation space.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural schematic diagram of a loop heat pipe;

FIG. 2 is a heat conduction schematic diagram of a heat conductive vaporchamber;

FIG. 3 is a heat conduction schematic diagram of a heat spreading vaporchamber;

FIGS. 4 and 5 are heat conduction schematic diagrams of a heatconductive vapor chamber based on a flat plate loop heat pipe; and

FIGS. 6 and 7 are heat conduction schematic diagrams of a heat spreadingvapor chamber based on a flat plate loop heat pipe.

In the drawings, 1: evaporator; 2: condenser; 3: reservoir; 4: vaporline; 5: liquid line; 6: capillary wick; and 7: gas/liquid line

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure is described in detail below in combination withaccompanying drawings and embodiments.

The present embodiment provides a vapor chamber based on a flat plateloop heat pipe, which may solve a conflicting requirement of theimprovement of the properties of the vapor chamber for the diameter of acapillary wick.

Embodiment 1: Heat Conductive Vapor Chamber

As shown in FIGS. 4 and 5, a flat plate loop heat pipe composed of anevaporator, a reservoir and a gas/liquid line is pre-buried in analuminum alloy heat spreading plate in a gluing or welding manner toform a vapor chamber based on the flat plate loop heat pipe. The vaporchamber is attached to a circuit board to be subjected to heatdissipation, so that the evaporator of the flat plate loop heat pipe isarranged in a region, attached to a biggest heat source (namely aposition with the greatest heat generation amount of the circuit board)of the circuit board, on the vapor chamber. The side, provided with avapor channel, of the evaporator is attached to the biggest heat source.The evaporator may be pre-buried into the aluminum alloy heat spreadingplate, or is only fixed in the aluminum alloy heat spreading plate. Theevaporator is exposed and directly attached to the biggest heat source.The liquid reservoir of the flat plate loop heat pipe is suspended, andis not connected with the aluminum alloy heat spreading plate in a heatconduction manner, so as to prevent heat leakage to the reservoir. “Heatsink attached regions” and “heat source attached regions” are arrangedon the vapor chamber. The “heat source attached regions” are regionsattached to heat sources (except the biggest heat source) on the circuitboard, and the “heat sink attached regions” are regions adopting acooling mode (cold sources) on the back surface of the vapor chamber, asshown in FIG. 5. The gas/liquid line led out from an outlet of theevaporator is disposed in a meandering manner between the “heat sinkattached regions” and the “heat source attached regions” on the vaporchamber. The gas/liquid line finally passes through the “heat sinkattached regions” and then returns to the reservoir of the flat plateloop heat pipe, as shown in FIG. 4. The gas/liquid line may be firstformed by a copper, stainless steel or titanium alloy pipeline sheetmetal, and then pre-buried in the aluminum alloy heat spreading plate ina gluing or welding manner.

Working principle: since the evaporator of the flat plate loop heat pipeis attached to the biggest heat source, liquid is evaporated into vaporin the evaporator, and the vapor flows to the “heat sink attachedregions” and releases heat, and then is condensed into liquid. Since thegas/liquid line is disposed in a meandering fashion between the “heatsource attached regions” and the “heat sink attached regions”, a liquidworking fluid absorbs heat in the “heat source attached regions” andthen is evaporated into vapor, and the vapor releases heat in the “heatsink attached regions” and then is condensed into liquid. This cycle isperformed for multiple times, and finally the working fluid flows backinto the reservoir after being condensed by the “heat sink attachedregions” into the liquid. In such cycle operation, a function ofconducting the heat of one or more heat sources to the “heat sinkattached regions” is realized.

Embodiment 2: Heat Spreading Vapor Chamber

A main difference of the heat spreading vapor chamber from the heatconductive vapor chamber is that: except “heat source attached regions”on the vapor chamber, other regions in no contact with heat sources areall used as “heat sink attached regions”. Therefore, a gas/liquid lineis disposed in a meandering fashion between the “heat source attachedregions” and other regions. The working principle of the heat spreadingvapor chamber is the same as that of the heat conductive vapor chamber.

The above contents are merely preferred embodiments of the presentinvention, but not intended to limit the protection scope of the presentinvention. Any modifications, equivalent replacements, improvements,etc. that are made without departing from the spirit and principle ofthe present disclosure shall all fall within the protection scope of thepresent disclosure.

1. A vapor chamber based on a flat plate loop heat pipe, wherein thevapor chamber is attached to heat sources, comprising: a heat spreadingplate; and a flat plate loop heat pipe composed of an evaporator, areservoir and a gas/liquid line; wherein the flat plate loop heat pipeis pre-buried in the heat spreading plate; wherein the evaporator isarranged on the heat spreading plate at the position of attachment tothe biggest heat source in the heat sources; wherein the reservoir isused to supply liquid to the evaporator; positions on the heat spreadingplate that are attached to other heat sources except the biggest heatsource in the heat sources are used as “heat source attached regions”,and positions on the heat spreading plate that are not attached to theheat sources are used as “heat sink attached regions”; wherein thegas/liquid line leading out from an outlet of the evaporator is disposedin a meandering fashion between the “heat source attached regions” andthe “heat sink attached regions” on the heat spreading plate, so that aliquid working fluid enters the “heat sink attached regions” afterabsorbing heat of the “heat source attached regions” and beingevaporated into vapor, and a gas working fluid releases heat in the“heat sink attached regions” and is condensed into liquid; andcirculation is performed hereby, and the working fluid finally flowsback into the reservoir after being condensed by the “heat sink attachedregions” into liquid, thus forming a loop.
 2. The vapor chamber based onthe flat plate loop heat pipe according to claim 1, wherein cold sourcesare arranged in the “heat sink attached regions” on one side or twosides of the heat spreading plate; and the gas/liquid line leading outfrom the outlet of the evaporator is disposed in a meandering fashionbetween the “heat sink attached regions” and the “heat source attachedregions” on the heat spreading plate.
 3. The vapor chamber based on theflat plate loop heat pipe according to claim 1, wherein the liquidreservoir is suspended, and is not connected with the heat spreadingplate in a heat conduction manner.
 4. The vapor chamber based on theflat plate loop heat pipe according to claim 1, wherein the evaporatoris exposed and directly attached to the biggest heat source in the heatsources.
 5. The vapor chamber based on the flat plate loop heat pipeaccording to claim 1, wherein the gas/liquid line is formed by a copper,stainless steel or titanium alloy pipeline sheet metal, and pre-buriedin the heat spreading plate in a gluing or welding manner.
 6. The vaporchamber based on the flat plate loop heat pipe according to claim 1,wherein the heat spreading plate is an aluminum alloy plate.
 7. Thevapor chamber based on the flat plate loop heat pipe according to claim2, wherein the liquid reservoir is suspended, and is not connected withthe heat spreading plate in a heat conduction manner.
 8. The vaporchamber based on the flat plate loop heat pipe according to claim 2,wherein the evaporator is exposed and directly attached to the biggestheat source in the heat sources.
 9. The vapor chamber based on the flatplate loop heat pipe according to claim 2, wherein the gas/liquid lineis formed by a copper, stainless steel or titanium alloy pipeline sheetmetal, and pre-buried in the heat spreading plate in a gluing or weldingmanner.
 10. The vapor chamber based on the flat plate loop heat pipeaccording to claim 2, wherein the heat spreading plate is an aluminumalloy plate.